Chemically modified elastomers and blends thereof

ABSTRACT

This invention relates to grafted ethylene-higher α-olefin polymers and blends thereof. Preferred grafted ethylene-higher α-olefin polymers are multimodal EPDM&#39;s having 5-40 weight % of a higher molecular weight, higher ethylene content, lower diene content fraction grafted with maleic anhydride. These polymers can then be used as modifiers for additional polymers such as polyamides, polyesters, and other EPDM&#39;s.

FIELD OF THE INVENTION

This invention relates to chemically modified elastomers, blends thereofand processes to produce them.

BACKGROUND OF THE INVENTION

Ethylene-Propylene copolymers and Ethylene-Propylene Diene Monomer(EP(D)M's) elastomers have been modified by various agents in the pastto improve their properties and compatibilities with other polymers. Inparticular, EP(D)M's were typically grafted with unsaturated carbonylderivatives to improve their compatibility to thermoplastics such aspolyamides (as taught in U.S. Pat. No. 3,972,961). Thermoplasticcomponents, particularly polyamide components, have been recentlyintroduced in the automotive industry to replace metallic parts. Thesecomponents, made of high molecular weight thermoplastics are generallyglass filled and produced by blow molding. In general, thermoplasticsare limited by processing problems. For example, polyamide showslimitations in the blowing phase because of its rather low melt strengthwhich results in parison tear and failure in the blow molding process.High molecular weight modifiers can be used to increase the meltstrength, provided however that (1) they can be easily dispersed withinthe thermoplastic, and (2) they do not increase the blend viscosity andlimit the cycle time in the blow molding phase. Thus, there is a need inthe art for a thermoplastic modifier that can be easily dispersed andthat does not substantially increase the blend viscosity versustraditional modifiers. The invention herein addresses this need byselecting a particular EPDM composition to be grafted and then blendedwith the thermoplastic. This combination meets the desiredEPDM/thermoplastic blend properties without the expected increase inmelt viscosity. Moreover, the selected EPDM composition shows increasedgrafting efficiency versus traditional EPDM compositions havingcomparable structures.

Art Disclosed for United States Purposes Includes:

JP 04220409 which discloses grafting styrene/acrylonitrile mixture ontoa blend of EPDM's of differing glass transition temperatures and U.S.Pat. No. 5,374,364 which discloses grafting EPDM with various monomersincluding crotonaldehyde.

SUMMARY OF THE INVENTION

This invention relates to a composition comprising an ethylene-higherα-olefin polymer composition grafted with at least 0.05 weight %,preferably at least 1 weight %, based upon the weight of the polymer, ofan unsaturated organic compound containing at least one carbonyl group,wherein-the ethylene-higher α-olefin composition comprises:

i) a first polymer fraction having a number average molecular weight offrom 10,000 to 500,000, an ethylene content of from 30 to 80 weight %and a diene content of from 1.0 to 12 weight %, based upon the weight ofthe polymer; and

ii) a second polymer fraction having a number average molecular weightof from 100,000 to 10,000,000, an ethylene content of from 40 to 90weight % and a diene content of from 0 to 12 weight %, based upon theweight of the polymer; provided that:

a) the second fraction has a higher molecular weight than the firstfraction,

b) the second fraction has an equal or higher ethylene content than thefirst fraction,

c) the weight ratio of diene in the first fraction to diene in thesecond fraction is at least 0.5/1, preferably 1/1, more preferably 2/1,

d) the Mw/Mn of each fraction is independently from 2 to 6.5, and

e) the first fraction comprises 60 to 95 weight % of the total polymercomposition.

This invention further relates to blends comprising the compositiondescribed above and one or more polymers selected from the groupconsisting of polyamides, polypropylenes, polyethylenes,ethylene-propylene copolymers, and ethylene-propylene-diene copolymers.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the viscosity/shear rate curves for a grafted polymeraccording to the invention and a commercially available grafted EPM.(The squares are the grafted EPDM 2 from Example 2 and the triangles areEP 4 (VA-1801)).

FIG. 2 shows the viscosity/shear rate curves for blends of Example 2.LEXT 2817 is a blend of the grafted EPDM 2 from Example 2 with PA-6 inan 80/20 ratio and LEXT 2812 is a blend of EP 4 (VA-1801) with PA-6 inan 80/20 ratio.

FIG. 3 shows the complex viscosity/shear rate curves for blends ofExample 2.

FIG. 4 shows dynamic moduli of the blends of Example 2.

FIG. 5 shows the viscosity/shear rate behaviour of the two blends inExample 2. LEXT 3817 is a blend of grafted EPDM-2 from Example 1 withUltramid B5 (80/20), and LEXT 3819 is a blend of EP-4 (CA-1801) withUltramid B5 (80/20).

DETAILED DESCRIPTION OF THE INVENTION

In a preferred embodiment this invention relates to a compositioncomprising an ethylene-higher α-olefin polymer composition grafted withat least 0.05 weight %, preferably 0.05 to 5 weight %, even morepreferably 0.2 to 3 weight %, based upon the weight of the polymer, ofan unsaturated organic compound containing at least one carbonyl group,wherein the ethylene-higher α-olefin composition comprises:

i) a first polymer fraction having a number average molecular weight offrom 10,000 to 500,000, an ethylene content of from 30 to 80 weight %,preferably 40 to 80 weight %, even more preferably 50-70 weight %, and adiene content of from 1 to 12 weight %, preferably 1.5 to 10 weight %,even more preferably 2 to 6 weight %, based upon the weight of thepolymer; and

ii) a second polymer fraction having a number average molecular weightof from 100,000 to 10,000,000, preferably 200,000 to 1,000,000, anethylene content of from 40 to 90 weight %, preferably 40 to 80 weight%, even more preferably 50-70 weight %, and a diene content of from 0 to12 weight %, preferably 0 to 8 weight %, even more preferably 0 to 6weight %, based upon the weight of the polymer; provided that:

a) the second fraction has a higher molecular weight than the firstfraction,

b) the second fraction has an equal or higher ethylene content than thefirst fraction,

c) the weight ratio of diene in the first fraction to diene in thesecond fraction can vary from 0.5 to 1, from 2.0 to 1 or even more (whenthe second fraction has no diene the ratio is of course infinity), inpreferred embodiments the ratio is at least 0.5 to 1, preferably atleast 0.8 to 1,

d) the Mw/Mn of each fraction is independently from 2 to 6.5, preferably2 to 5, even more preferably 2 to 4 and

e) the first fraction comprises 60 to 95 weight %, preferably 70-95weight % of the total polymer composition.

Preferred ethylene-higher α-olefin polymer compositions used in thisinvention are more fully described in and can be prepared according tothe procedures in EPA 0 227 206 B1 (which is equivalent to U.S. Pat. No.4,722,971). In general, however the ethylene-higher α-olefin polymersare copolymers of ethylene and a C₃ to C₈ α-olefin, preferably propyleneand an optional diene, preferably a non-conjugated diene. Preferreddienes include straight chain alicyclic dienes (such as 1,4 hexadiene),branched chain dienes, acyclic dienes (such as 5-methyl-1,6-hexadiene),single ring alicyclic dienes (such as 1,4-cyclohexadiene), multi ringalicyclic fused and bridged ring dienes (such as dicyclopentadiene),bridged ring dienes (such as alkenyl, alkylidene, cycloalkenyl andcycloalkylidene norbornenes) and the like. Particularly preferred dienesinclude 5-ethylidene-2-norbornene, methylene norbornene and vinylnorbornene.

In a preferred embodiment these ethylene-higher α-olefin compositionpolymers have a branching index between 0.1 and 0.8, more preferablybetween 0.2 and 0.7.

The ethylene-higher α-olefin polymer compositions are chemicallymodified by reaction with an unsaturated organic compound containing atleast one carbonyl group. The term “graft” shall mean the process ofreacting the unsaturated organic compound and the ethylene-higherα-olefin polymer and an optional free radical initiator and the term“grafted polymer” shall mean the product of the reaction between theunsaturated organic compound and the ethylene-higher α-olefin polymer.The grafting may be accomplished by any technique known in the art suchas those disclosed in U.S. Pat. Nos. 3,236,917; 4,950,541 and 5,194.Typically, the polymer to be grafted, the unsaturated organic compoundand an optional free radical initiator are all introduced into areaction zone, heated and or mixed and allowed to react. One of the manypossible methods to graft the ethylene-higher α-olefin polymercompositions would be introducing the polymer into a mixing device, suchas a single or twin screw extruder or an internal mixer, heating thepolymer until it is molten, injecting the unsaturated organic compoundand the free radical initiator into the mixing device and mixing thecomponents under high or low shear conditions. The unsaturated organiccompounds may be added as a neat compound, as part of a master batch, oras a supported compound. The support is typically a polymer but may beany of the well known inorganic supports.

Typical free radical agents include well known peroxides, such as thedialkyl peroxides, (dicumylperoxide,2,5-dimethyl-2,5bis(tertbutylperoxy)hexene-3, tertio butylcumylperoxide,2,5-dimethyl-2,5bis(tertbutylperoxy) hexene, diacylperoxide (dibenzoylperoxide, dilauryl peroxide), peroxyesters (tert butyl peroxyacetate,tert butyl peroxypivalate, AIBN (azoisobisbutyronitrile) peroxyketones,monoperoxycarbonates, and commercially available peroxides, such as theLupersol™ products.

Unsaturated organic compounds containing at least one carbonyl group arethose compounds containing at least one unsaturation and at least onecarbonyl group (—C═O). Representative compounds include the carboxylicacids, anhydrides, esters and their salts, both metallic andnon-metallic. Preferred compounds contain ethylenic unsaturationconjugated with a carbonyl group. Preferred examples include maleicacid, fumaric, acrylic, methacrylic, itaconic, crotonic, a-methylcrotonic and cinnamic acids, their anhydride, ester and saltderivatives, as well as glycidylmethacrylate, glycidyl acrylate or otherglycidyl compounds. Maleic anhydride is a preferred unsaturated organiccompound.

A desirable aspect of this invention is that the ethylene-higherα-olefin polymers described above typically have an unexpectedly goodgrafting efficiency of at least 20%, preferably 30%, even morepreferably at least 40% better than comparable monomodal branched EPDMterpolymers. Grafting efficiency is the weight of the organic compoundgrafted as determined by FTIR divided by the weight of the organiccompound fed to the extruder.

In a particularly preferred embodiment the grafted polymer producedherein typically has the desirable combination of

1. a melt flow rate (MFR, as measured by ASTM D 1238 10 kg, 230° C.) of3 g/10 min or less, preferably 0.2 to 3, even more preferably 0.2 to 1,and

2. a low shear rate viscosity, (as measured by capillary rheometer at235° C. and at a shear rate of 10 sec⁻¹ according to ASTM 3835-95) above4000 Pa·sec, preferably above 5000 Pa·sec, and

3. a high shear rate viscosity, (as measured by capillary rheometer at ashear rate of 1000 sec⁻¹ according to ASTM 3835-95 )of 1000 Pa·sec orless, preferably below 500 Pa·sec, and

4. a level of unsaturated organic compounds of 0.5 to 20 weight %, basedupon the weight of the copolymer. The unsaturated organic compoundscontent is measured by FTIR (Fournier Transformed Infraredspectroscopy). The reaction products are compressed at t°≈165° C. intothin films from which infrared spectra were taken using a MattsonPolaris Fourrier Transformed Infrared spectrometer at 2 cm⁻¹ resolutionwith the accumulation of 100 scans. The relative peak height of theanhydride absorption bond at 1790 cm⁻¹ and of the acid absorption(coming from the anhydride hydrolysis in the air) at 1712 cm⁻¹ comparedwith a bond at 4328 cm⁻¹ serving or internal standard or taken or ameasurement of the MA content.${\% \quad {MA}} = {k\frac{{A1790} + {A1712}}{A4328}}$

 k being determined * internal calibration with standard.

5. a gel level of 5% or less preferably 3% or less even more preferablyof 1% or less, most preferably of 0%I(as measured by extraction withrefluxing xylene in a soxlet for 8 hours).

The grafted polymer may then be blended with one or more additionalpolymers. Preferred additional polymers include plastics [HDPE (Highdensity polyethylene), LDPE (low density polyethylene), LLDPE (linearlow density polyethylene), VLDPE (very low density polyethylene), PP(polypropylene)]; elastomers [ethylene-propylene copolymers, ethylenepropylene diene terpolymers, ethylene α-olefin copolymers,polyisobutylene, polybutene, butyl rubber, halobutyl rubber,polyisobutylene co-paramethylstyrene rubber, brominated polyisobutyleneco-paramethyl styrene rubber, nitrile rubber, natural rubber, styrenebutadiene rubber, epichlorhydrin, chlorinated polyethylene, ethyleneacrylic acid acrylic ester rubber]; plastomers [ethylene α-olefincopolymers]; engineering thermoplastics [polyamide, polybutyleneterephtalate, polyethylene terephtalate, polycarbonate, polyacetal), PVC(polyvinyl chloride), ethylene non α-olefin copolymers, EAA (ethyleneacrylic acid copolymers), EMA (ethylene methyl acrylate copolymers), EVA(ethylene vinyl acetate)]; ionomers, [EVOH (ethylene vinyl alcoholcopolymers), ECO (ethylene carbon monoxide copolymer)]; and the like.

The grafted polymer and the additional polymers may be combined by anymeans known in the art such as melt blending, dry blending, tumblemixing, barrel mixing, single or twin screw extrusion, mixing on aBanbury mixer, and the like, with melt blending being preferred. Theamount of the components in the blend will depend on the application anddesired end use. For example for blow molded uses the grafted polymer ispresent at 5 to 40, preferably 10 to 30 weight % based upon the totalweight of the grafted polymer and the additional polymer.

A particularly advantageous use for the grafted polymers of thisinvention includes use as modifiers for polyamide (PA)basedcompositions. These grafted polymers can be used as modifiers for PAtoughening where they show superior impact strength at room temperature.More specifically they can be used in glass filled PA compoundsdeveloped for blow molding applications. One of the grafted polymers'attractive properties resides in their rheology. These polymers, beingshear sensitive, show higher viscosity at low shear rate and lowerviscosity at high shear rates. When blended with high number averagemolecular weight PA, the blend also displays a shear thinning behaviour.At low shear rates, typical of the blowing phase, the blend has a highviscosity which will translate in a higher melt strength. These blendswill thus show an increased resistance to failure and tear during theblowing operation. At high shear rates, typical for injection molding,the blend has a similar viscosity to blends containing a lower viscositylinear ethylene propylene rubber grafted with maleic anhydride and hasthus no processing penalty. The grafted polymers can also be used inthermoset compounds as adhesion promoters to flock or to aramid fibers.Finally another application is their use in thermoplastic elastomerblends with polyamides where after blending, these polymers could bevulcanized to give a dynamically vulcanized alloy. Dynamicallyvulcanized alloys and process to make them are described in U.S. Pat.Nos. 5,157,081; 5,100,947; 5,073,597; and 5,051,478.

The ethylene-higher α-olefin polymers described herein give highergrafting (as compared to traditional highly branched EPDM's) when meltreacted with a peroxide and an unsaturated compound containing both anunsaturation and a conjugated carbonyl function. These grafted polymersare highly shear sensitive and are thus ideal modifiers for theproduction of blow molded toughened thermoplastic parts where highviscosity at low shear rate and low viscosity at high shear rate aresuitable.

EPDM polymers having long chain branching show lower grafting levelsversus linear EPDM when melt reacted with an unsaturated compound and aperoxide. Surprisingly, the ethylene-higher α-olefin polymers describedherein which it is believed also have long chain branching show 30-40%increase in grafting efficiency when reacted under the same conditions.

Number average molecular weight of the second fraction can be calculatedaccording to the equation Mn_(T)=Mn_(F1) ^(α)*Mn_(F2) ^((1−α)) whereMn_(T) is the number average molecular weight of the final polymer,Mn_(F1) the number average molecular weight of the first fraction,Mn_(F2) is the number average molecular weight of the second fractionand α is the weight percent of the first fraction.

EXAMPLES

Flexural modules was measured according to DIN 53457.

Tensile properties were measured according to DIN 53457.

Notched Izod Impact was measured according to ISO 180.

Notched Charpy Impact was measured according to ISO 179.

MVR (melt volume rate) was measured according to ISO 1133.

MFR (melt flow rate) was measured according to ASTM D 1238, (230° C., 10kg).

Viscosity is measured by capillary rheometer according to ASTM 3835-95

Mw and Mn are measured by gel permeation chromatography usingpolyisobutylene standards on a Waters 150 gel permeation chromatographdetector and a Chromatix KMX-6 on line light scattering photometer. Thesystem is used at 135° C. with 1,2,4-trichlorobenzene as the mobilephase. Showdex (from Showa Denks America, Inc.) polystyrene gel columns802, 803, 804 and 805 were used. This technique is discussed on “LiquidChromotography of Polymers and Related Materials III” J. Cazes editor,Marcel Dekker, 1981. No corrections for column spreading were employed.Mw/Mn was calculated from elution times. The numerical analyses wereperformed using the commercially available Beckman/CIS LALLS software inconjunction with the standard Gel Permeation package. The branchingindex (BI) of a ethylene-higher α-olefin diene is determined using abranching index factor. Calculating this factor requires a series ofthree laboratory measurements of polymer properties in solution. (SeeVerstrate, Gary, “Ethylene-Propylene Elastomers,” Encyclopedia ofPolymer Science and Engineering, 6, second edition, 1986) These are:

i) weight average molecular weight(Mw, LALLS) measured using low anglelaser light scattering (LALLS) technique subsequent to a gel permeationchromatograph (GPC);

ii) weight average molecular weight(Mw, DRI) and viscosity averagemolecular weight, (Mv, DRI) using a differential refractive indexdetector (DRI) with GPC and

iii) inherent viscosity (IV) measured in Decalin at 135° C.

The first two measurements are obtained in a gel permeationchromatograph (GPC) using a filtered dilute solution of the polymer intri-chloro benzene. An average branching index (BI) is defined as:

 BI=((Mv,br)×(Mw,DRI))+((Mw,LALLS)×(Mv,DRI))

where Mv,br=k(IV)^(1/a); Mv,br is viscosity average molecular weight forbranched polymer and “a” is the Mark-Houwink constant (=0.759 for anethylene, α-olefin, non-conjugated diene elastomeric polymer in decalinat 135° C.) “k” is a constant with a value of 2.47×10⁻⁴.

From the equation if follows that the branching index for a linearpolymer is 1.0 and for branched polymers the extent of branching isdefined relative to the linear polymer. Since at a constant Mn,(Mw)_(branch) is greater than (MW)_(linear), BI for a branched polymeris less than 1.0, an a smaller BI value denotes a higher level ofbranching. It should be noted that this method is only indicative of therelative degree of branching and not a quantified amount of branching aswould be determined using a direct method such as NMR.

EPDM 1 is an ethylene-propylene ethylidene norbornene terpolymer havingan MFR of 1.0 g/10 min, an ethylene content of 62 wt %, a diene contentof 5.7 wt %, an Mw/Mn of 2.8 and a BI of 0.7.

EPDM 2 is an ethylene-propylene-ethylidene norbornene terpolymer havingan MFR of 0.3 g/10 min, an ethylidene norbornene content of 5.7 wt %, anMw/Mn of 3.2 and a BI of 0.6, a low shear rate (10 sec⁻¹) viscosity of20,000 Pa·s at 235° C. and a high shear rate (1000 sec⁻¹) viscosity of700 Pa·s at 235° C. EPDM 2 also has 55 wt % ethylene, and 5.7 wt % dienein first fraction, 55 wt % ethylene and 5.7 wt % diene in the secondfraction, an Mn in the first fraction of 67,000, an Mn in the secondfraction of 300,000, an Mw/Mn of 5 in the first fraction and an Mw/Mn of4.7 in the second fraction.

EPDM 3 is a bimodal EPDM having an MFR of 1.3 g/10 min, an ethylenecontent of 50%, a diene content of 5.7 weight %, an Mw/Mn of 3.5 and aBI of 0.6.

Ultramid B3™ is a polyamide—6 polymer available from Bayer having an MVR(melt volume rate) at 275° C., under a weight of 5 kg, of 130 ml/min.

Ultramid B5™ is a high molecular weight polyamide—6 polymer availablefrom Bayer having an MVR (melt volume rate) at 275° C., under a weightof 5 kg, of 8 ml/min.

EP 4 (VA 1801) is an ethylene-propylene copolymer having an MFR of 9g/10 min grafted with 0.7 weight % of maleic anhydride.

Example 1

EPDM 2 and 3 were compared to a traditional long chain branched EPDMpolymer (EPDM 1) (Table 1). These polymers were melt functionalized on anon-intermeshing counter-rotating twin screw extruder (30 mm, L/D=48)under the following conditions: 94-96 weight % of the EPDM, 4-6 weight %of Accurel MA 903 (50% maleic anhydride in PE), 0.8 to 1.5 weight % of a10% solution of Luperox 130, at a polymer feed rate of 7 kg/hr, a screwspeed of 200 rpm, over four temperature zones of 170, 200,210, 210° C.with the die at 200° C. The polymers were added to the feed hopper withmaleic anhydride which was PE supported (50 wt %); after melting, theperoxide (LUPEROX™ 130) at a 10% concentration in mineral oil was added.Excess reagents were removed with vacuum prior to polymer recovery. Theconversions, reported in table 2, indicate that the grafting of EPDM's 2and 3 is more efficient than the grafting of the EPDM 1.

A grafted EPDM 2 (MFR 1.1 g/10 min (230° C., 10 kg) having 0.9 weight %maleic anhydride) was then blended with Ultramid B3 at 15 and 20 weight%. The viscosity/shear rate curves for both compositions are presentedin FIG. 1 (squares are the EPDM 2 (grafted with maleic anhydride) andtriangles are the EP 4 (VA1801)).

The two grafted polymers were blended with Ultramid B3 on anintermeshing co-rotating twin screw extruder (34 mm, L/D=36) accordingto the following conditions: 80 and 85 weight % of the Ultramid B3, 20and 15 weight % of the grafted polymer, at a feed rate of 10 kg/hour, ascrew speed of 100 rpm over ten temperature zones set at the followingtemperatures (° C.) 230, 230, 230, 230, 210, 210, 210, 210, 210, 230.The viscosity/shear rate behaviour of the two blends are depicted inFIGS. 2 and 3. The former figure is generated by measuring theviscosities on a capillary rheometer at 235° C. with a 20/1 L/D diewhereas the later one is generated from small amplitude oscillatorymeasurement performed on a Rheometrics Mechanical Spectrometer (RMS-800)at 230° C. Both figures confirm the higher viscosity of the grafted EPDM2 blend at low shear rates whereas a much lower difference is observedat higher shear rates. Comparison of the dynamic shear modulus of thetwo blends also shows a much higher value for the grafted EPDM 2 blend.As a result this blend will show higher melt strength and higherresistance to failure versus the blend with the traditional modifier.The blends were then tested for Notched Izod impact strength and NotchedCharpy impact. The grafted EPDM 2 also confers higher room temperatureimpact strength to the blend versus the traditional modifier (see table3).

TABLE 1 EPDM 1 EPDM 2 EPDM 3 ML₍₁₊₄₎, 125° C. 52 89 54 wt % ethylene 6250 50 wt % ENB 5.7 5.7 5.7 Mw/Mn (DRI) 2.8 3.2 3.5 BI 0.7 0.6 0.6 BI =branching index ENB = 5-ethylidene-2-norbornene

TABLE 2 (Grafting Efficiency) EPDM 1 EPDM 2 EPDM 3 MA feed % 2 3 3 2 3 32 3 Peroxide feed 0.08 0.12 0.15 0.08 0.12 0.15 0.08 0.15 % Temp. (° C.)201- 209- 201- 200- 202- 201- 199- 198- 200 210 207 207 210 210 208 209MFR g/10 min 1.6 2.06 1.04 1.0 0.94 0.75 0.1 0.7 (230° C. 10 kg) MA wt %0.54 0.88 1.11 0.79 1.24 1.4 0.82 1.26 (a.o.) Grafting 27 29 37 40 41 4741 42 Efficiency (%) a.o. = after oven

TABLE 3 (Blend Properties) EP 4 (VA- EPDM 2 (-g- EP 4 (VA- EPDM2 (-g-1801)-20% MA)-20% 1801)-15% MA)-15% UB3 - 80% UB3 - 80% UB3 - 85% UB3 -85% Notched Izod 75 100 81 101 Impact (kJ/m²) room temp Notched Izod 71 93 53  83 Impact (kJ/m²) 0° C. Notched 49  60 43  58 Charpy Impact(kJ/m²) room temp Notched 37 (nb)  52 21 (b)  27 (b) Charpy Impact(kJ/m²) 0° C. nb = no break b = break UB3 is Ultramid B3

Another benefit of this invention is the grafting efficiency of thepolymers described herein. In a preferred embodiment the polymer has agrafting efficiency of 35% or more, preferably 40% or more, even morepreferably 45% or more.

Example 2

Grafted EPDM 2 and EP-4 were blended with Ultramid B5 according to theprocedure described in Example 1, except that the temperature profilewas 260-260-260-230-230-230-230-230-230-260° C. and screw speed was 150rpm. The blends were then tested for Notched Izod impact strength andNotched Charpy impact and other properties. The data are reported inTable 4.

TABLE 4 Ultramid B5 Ultramid B5 EPDM-2(-g-MA) EP4(VA 1801) (80/20)(80/20) Flex. Mod. cond. MPa 1686  1648  Flex. Mod. dam. MPa 1718  1668 Tensile properties on samples cond. Stress at Maxload Mpa 58 52 Stressat break Mpa 57 52 El. at break % 99 114  E-modulus MPa 1854  1796 Tensile properties on samples dam. Stress at Maxload Mpa 57 50 Stress atbreak Mpa 56 47 El. at break % 94 82 E-modulus MPa 1955  1871  NotchedIzod RT dam. kJ/m² 128  86 Izod RT (cond.) kJ/m² 119  69 Izod 0° C.kJ/m² 131  108  Izod −10° C. kJ/m² 134  111  Izod −20° C. kJ/m² 132 105  Izod −30° C. kJ/m² 120  92 Izod −40° C. kJ/m²  27*  21* NotchedCharpy RT dam. kJ/m² 56 34 Charpy RT (cond.) kJ/m² 72 53 Charpy 0° C.kJ/m² 64 47 Charpy −10° C. kJ/m² 63 51 Charpy −20° C. kJ/m² 58 44 Charpy−30° C. kJ/m² 43 32 Charpy −40° C. kJ/m²  19*  21* MFR 275° C./2.16 kgg/10 min    0.05    0.28 MFR 275° C./5.00 kg g/10 min    0.41    1.61MFR 275° C./10.00 kg g/10 min   1.7   5.9 MFR 275° C./21.16 kg g/10 min  8.6 26 * = samples broken

Note from Table 4 that the EPDM 2 blend has better notched Izod impactfrom room temperature down to −40° C. compared to the VA-1801 or EP-4.

The viscosity shear rate behaviour of the two blends is depicted in FIG.5. The figure was generated from small amplitude oscillatorymeasurements performed on a Rheometrics Mechanical Spectrometer(RMS-800) at 260° C. FIG. 5 confirms the higher viscosity of the graftedEPDM 2 blend at low shear rates whereas a much lower difference isobserved at higher shear rates.

As is apparent from the foregoing general description and the specificembodiments, while forms of the invention have been illustrated anddescribed, various modifications can be made without departing from thespirit and scope of the invention. Accordingly, it is not intended thatthe invention be limited thereby.

What is claimed is:
 1. A polyamide blow molding process comprisingblending polyamide with 5 to 40 weight percent of a compositioncomprising an ethylene-C₃ to C₈ α-olefin polymer composition graftedwith at least 0.05 weight %, based upon the weight of the polymer, of anunsaturated organic compound containing at least one carbonyl group,wherein the ethylene-C₃ to C₈ α-olefin composition comprises: i) a firstpolymer fraction having a number average molecular weight of from 10,000to 500,000, an ethylene content of from 30 to 80 weight % and a dienecontent of from 1.5 to 10 weight %, based upon the weight of thepolymer; and ii) a second polymer fraction having a number averagemolecular weight of from 100,000 to 10,000,000, an ethylene content offrom 40 to 90 weight % and a diene content of from 0 to 8 weight %,based upon the weight of the polymer; provided that: a) the secondfraction has a higher molecular weight than the first fraction, b) thesecond fraction has an equal or higher ethylene content than the firstfraction, c) the weight ratio of diene in the first fraction to diene inthe second fraction is at least 0.5/1, d) the Mw/Mn of each fraction isindependently from 2 to 6.5, and e) the first fraction comprises 95 to60 weight % of the total polymer composition; and blow molding theblend.
 2. The process of claim 1 wherein the ethylene-α-olefin polymerhas a branching index of 0.1 to 0.8.
 3. The process of claim 1 or 2wherein the grafted ethylene-α olefin polymer has a low shear viscosityof 5,000 Pa·sec or more, a high shear viscosity of 1,000 Pa·sec or less,and MFR of 3 g/10 min or less and a gel content of less than 5%.
 4. Theprocess of claim 1 wherein the grafted ethylene-α olefin polymer isgrafted with at least 1 weight % of the unsaturated organic compounds.5. The process of claim 1 wherein the polymer composition has a graftingefficiency of 35% or more.
 6. The process of claim 1 wherein the blendfurther comprising glass fibers.
 7. The process of claim 1 wherein thepolymer composition has a melt flow rate of 3 g/10 min or less.